The present invention relates to a new and improved construction of steam power plant containing a pressure-fired stem generator or steam-generating unit with fluidized bed firing.
Generally speaking, the steam power plant of the present development is of the type containing a loading or charging set or group composed of a gas turbine and a compressor, driven by the flue gases of the steam generator. The loading set feeds the compressed combustion air below the fluidized bed, in order to form thereof a fluidized or vortex layer or flow. Additionally, there are provided devices for the separation, filtering and withdrawal of the dust-like contaminants contained in the flue gases and for controlling and regulating the steam output or capacity delivered to the steam turbogenerator set.
With heretofore known pressure-fired steam generators containing fluidized bed firing the heat of combustion is transmitted for the most part to the water tubes located in the fluidized or vortex layer of the fluidized bed firing arrangement, in order to achieve cooling of the vortex layer fluidized bed and to obtain an optimum combustion temperature.
A decisive drawback of such steam generators resides in the fact that owing to the high temperatures the tubes located in the vortex layer are subjected to corrosion attack by the combustion gases, and thus, must be replaced in a relatively short amount of time.
Instead of having cooling tubes arranged in the vortex layer or flow the heat of combustion of the vortex layer also can be withdrawn by having an increased air throughput. However, this is associated with the drawback that then the turbine must handle a larger volume of flue gas and the load or charging set and equally the filter must be dimensioned to be correspondingly larger.